WO2012062331 discloses a fish filleting machine comprising a number of stations for continuous filleting of fish, where de-capitated and gutted fish is placed right side up, i.e. the back of the fish upwards and front end foremost in an in-feed channel. The fish filleting machine comprises six stations, where a first station comprises means for engaging the fish and centring the fish relative to a vertical plane of the machine, such that lower sides of the fish are arranged on opposite sides of the plane. A second station comprises means for detecting and registering the vertical extent of the lower edges of the fish and the back of the fish. A third station comprises means for fixating the back of the fish, and cutting means for cutting slits in the back of the fish, the slits having an extent at least along either side of the protruding back fin. A fourth station comprising articulated cutting means, where the articulated cutting means are arranged on either side of the vertical plane, suitable for cutting/trimming at least a part of the lowermost sides and/or edges of the fish. A fifth station where upper cutting means are positioned along the vertical plane for cutting the fish meat free from the vertebrae of the fish. A sixth station comprises means for cutting vertically on either side of the vertebrae and a seventh station for directing the bone-free fillets to further processing.
The second station mentioned above detects the geometrical size of the sides of the fish by means of registering the vertical extent of the lower edges of the fish relative to the back, and this data is used as input data in trimming the belly part at the fourth station. However, the measuring arrangement for measuring the geometrical size of the sides of the fish and the configuration of the fourth station can result in inaccuracy in the geometrical measurement and thus in inaccurate in trimming the belly part of the fish.